I completed the base. I centered it using box itself and marked that outline with blue tape. Then without the box in place, I penciled in the 5/8 depth of the walls so I could then mark the location for the screws. Not sure if I need to go back and enlarge these (for wood movement). I used a Rockler drill guide I bought a while back when the "jig" was on sale and have to say I really like it. Allowed me to not angle the drill and was pretty easy to set up. Much better than my drill press. Used larger size bit to create a countersink.
I then attached the base to the box with double-sided tape in order to drill pilot holes into the sides as well. This ensured I had everything perfectly lined up for future attachment of the base.
That was followed by more sanding to clean up any marks I made while handling the box and base. The final touch was to chamfer the top edge. Since the cross was attached, and the top is raised, I couldn't use my router table. I could have used my handheld router and ran the router up the side, but decided to use more meaningful (to my anyway) approach by using the little plane I was given that had been my grandpa's plane. Had to make several adjustments and tests on scrape, but finally got it so I could take a couple passes to get a small chamfer.
The final post will be under projects with the finish applied - here's a sneak peek (still need to do the final buffing...but this walnut did not disappoint!!).